Continuous process for the production of polyether polyols

ABSTRACT

A continuous alkoxylation process for the production of polyether polyols is disclosed. The process comprises the use of a plurality of reaction modules each having an outer tube and an inner tube with annular chamber between them. A spiral reaction tube is spaced from the inner tube and winds around the inner tube within the annular chamber. The spiral reaction tube includes an inlet and an outlet, each of which extend through said outer tube. A heat exchange medium flows through the annular chamber and controls the reaction temperature in the spiral reaction tube. The process comprises continuously forming an initial reaction mixture of at least one [alkaline] alkylene oxide and an initiator having at least one reactive hydrogen which is reactive to the [alkaline] alkylene oxide. Continuously flowing the initial reaction mixture through a first spiral reaction tube having an internal diameter and a spiral diameter that promote a pseudo-turbulent flow of the initial reaction mixture through the first spiral reaction tube to form a reaction product. Then flowing the reaction product into a second spiral reaction tube and adding a catalyst and an [alkaline] alkylene oxide to the reaction product, the second spiral reaction tube having an internal diameter and a spiral diameter that promote a pseudo-turbulent flow of the reaction product, the catalyst and the [alkaline] alkylene oxide in the second spiral reaction tube.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to a method for producingpolyether polyols and, more particularly, to a continuous process forthe production of polyether polyols.

[0002] Polyols are generally defined as compounds that include aplurality of hydroxyl groups. They can be simple polyols or as complexas a 10,000 Dalton polyether polyol comprising a heteric mixture ofethylene oxide and propylene oxide. Polyols, particularly polyetherpolyols, are useful when combined with isocyanates to formpolyurethanes. To produce a high quality polyurethane it is necessary tobegin with a high quality polyol. By high quality it is meant a polyolthat has a very narrow size distribution and a generally uniformcomposition. Typically polyols are produced commercially in a batchreactor. A batch reactor is a large reactor chamber that includes andagitator and a thermal jacket. The reactants are added in bulk to thereactor under pressure and the reaction proceeds for hours and sometimesdays. One problem with batch reactors is that thermal control can behard to achieve and the entire reaction must be run at a commontemperature. Also the batch reactor needs to be shut down to remove thereaction product, thus slowing production.

[0003] It would be advantageous to design a continuous reactor assemblyto permit the continuous formation of high quality polyether polyols. Itwould be most advantageous to design the reactor assembly in a mannerthat promotes turbulent or pseudo-turbulent flow of the reactants andthat is modular to permit rapid and easy modification of the assembly tomeet the design requirements of a variety of polyols. It would beadditionally beneficial to design the reactor assembly to permitdifferent reaction temperatures at different points in the reaction.

SUMMARY OF THE INVENTION

[0004] In general terms, this invention provides a continuous reactorassembly and a method of using the same to form polyether polyols. Thereactor assembly is of a modular design that permits rapid and easymodification of the reactor to accommodate different reactionrequirements imposed by the chosen product. The reactor assemblyadditionally provides the ability to prepare a polyol that requiresdifferent reaction temperatures at different points in the reaction.

[0005] In a first embodiment the method of the present inventioncomprises a continuous process of forming polyether polyols comprisingthe steps of: continuously forming an initial reaction mixture of atleast one [alkaline] alkylene oxide and an initiator having at least onereactive hydrogen which is reactive to the [alkaline] alkylene oxide;continuously flowing the initial reaction mixture through a first spiralreaction tube having an internal diameter and a spiral diameter thatpromote a pseudo-turbulent flow of the initial reaction mixture throughthe first spiral reaction tube to form a reaction product; flowing thereaction product into a second spiral reaction tube operably connectedto the first spiral reaction tube and adding a catalyst and an[alkaline] alkylene oxide to the reaction product, the second spiralreaction tube having an internal diameter and a spiral diameter thatpromote a pseudo-turbulent flow of the reaction product, the catalystand the [alkaline] alkylene oxide in the second spiral reaction tube;and continuously flowing a heat exchange medium around said first andsaid second spiral reaction tubes, said heat exchange mediumestablishing and maintaining a reaction temperature between 130° C. and250° C. in said first and said second spiral reaction tubes.

[0006] Another embodiment of the method of the present inventioncomprises a continuous process of forming polyether polyols comprisingthe steps of: continuously forming an initial reaction mixture ofethylene oxide and an aromatic initiator in the absence of a catalyst,the aromatic initiator having at least one reactive hydrogen which isreactive to the ethylene oxide; continuously flowing the initialreaction mixture through a first spiral reaction tube having an internaldiameter and a spiral diameter that promote a pseudo-turbulent flow ofthe initial reaction mixture through the first spiral reaction tube toform a reaction product; flowing the reaction product into a secondspiral reaction tube operably connected to said first spiral reactiontube and adding a catalyst and an [alkaline] alkylene oxide to thereaction product, the second spiral tube having an internal diameter anda spiral diameter that promote a pseudo-turbulent flow of the reactionproduct, the catalyst and the [alkaline] alkylene oxide in the secondspiral tube; surrounding the first and the second spiral reaction tubewith a heat exchange medium, the heat exchange medium establishing andmaintaining a reaction temperature between 130° C. and 250° C. in thefirst and the second spiral reaction tubes; and pressurizing the firstand the second spiral reaction tube at a pressure between 200 to 1500pounds per square inch, thereby maintaining the ethylene oxide and the[alkaline] alkylene oxide in a liquid state.

[0007] These and other features and advantages of this invention willbecome more apparent to those skilled in the art from the followingdetailed description of the presently preferred embodiment. The drawingsthat accompany the detailed description can be described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a sectional view of a reaction module;

[0009]FIG. 2 is a schematic view of a first embodiment of a continuousreactor;

[0010]FIG. 3 is a schematic view of another embodiment of a continuousreactor;

[0011]FIG. 4 is an alternative embodiment of the continuous reactorshown in FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0012] Within the several views described below like components aregiven the same reference numerals.

[0013] A reactor module is generally indicated at 20 in FIG. 1. Reactormodule 20 comprises an outer tube 22 which defines an annular chamber25. In a preferred embodiment, the module 20 further includes an innertube 24, with the annular chamber 25 defined between the inner tube 22and the outer tube 24. Reactor module 20 further includes an upperflange 26 opposite a lower flange 28. A heat exchange medium inlet 30extends through the outer tube 22 into the annular chamber 25 and a heatexchange medium outlet 32 also extends through the outer tube 22 intothe annular chamber 25. In one embodiment, support rods 34 are securedto an inner wall 33 of the outer tube 22 and extend toward the innertube 24. Alternatively, the support rods 34 may be secured to inner tube24 and extend toward outer tube 22.

[0014] A spiral reaction tube 36 is spaced apart from and spirals aroundthe inner tube 24. Spiral reaction tube 36 rests on support rods 34 inthe annular chamber 25. Spiral reaction tube 36 has a spiral diameter d1that is preferably approximately 1 to 2 inches less than the innerdiameter of outer tube 22. Thus, spiral reaction tube 36 closely followsthe inner contour of outer tube 22 which can be varied between about twofeet and ten feet in diameter. The spiral reaction tube 36 is preferablyformed from stainless steel, but as is apparent to one of ordinary skillin the art, tube 36 could be formed of other materials so long as it iscompatible with the desired reaction as described below. The internaldiameter of the spiral reaction tube 36 can vary between about 0.25 to3.0 inches depending on the operating parameters, as more fullydescribed below. The length of the spiral reactor tube 36 can varybetween about 20 feet and several hundred feet depending on therequirements of the reaction. Preferably, the length and diameter ofspiral reaction tube 36 are chosen to ensure that any reactantsintroduced at an inlet 38 have a sufficient residence time to permit asubstantially complete reaction between the reactants before the productof the reactants reaches an outlet 40. Furthermore the internal diameterand the spiral diameter d1 of the spiral reaction tube 36 arespecifically designed to ensure a largely turbulent or pseudo-turbulentflow, defined as a flow with eddy current mixing off a continuouslycurved wall, of reactants through the spiral reaction tube 36. Thisturbulent flow greatly increases the efficiency of the reaction,especially for polyether polyol formation. As described below, thevelocity of the flow rate of reactants in the spiral reaction tube 36 isalso preferably chosen to provide turbulent flow. The spiral reactiontube 36 inlet 38 and outlet 40, both extend beyond the outer tube 22.Both the inlet 38 and the outlet 40 include connectors (not shown) thatpermit feed lines (see FIGS. 2 and 3) to be connected to each.

[0015] Adjacent the upper flange 26 and the lower flange 28 is a seal 60(see FIGS. 2 and 3) that seals the annular chamber 25 and a space 42defined by an inner wall 44 of the inner tube 24. In a preferredembodiment, the inner tube 24 includes perforations (not shown) thatpermit fluid communication between the annular chamber 25 and space 42.A heat exchange medium 46 continuously flows from heat exchange mediuminlet 30 through annular chamber 25 and out of heat exchange mediumoutlet 32 and then recirculates through a heat exchanger 58 (FIGS. 2 and3). The flow of the heat exchange medium 46 is preferably turbulentwithin the annular chamber 25. The heat exchange medium 46 may also flowthrough space 42, which can serve as a large heat sink to maintain areaction temperature within the spiral reaction tube 36.

[0016] A schematic of a continuous reactor assembly is shown generallyat 50 in FIGS. 2 and 3. Continuous reactor assembly 50 comprises aseries of modules including a first module 52, a second module 54, andadditional modules 56 stacked on top of each other and connected viafasteners (not shown) on their respective upper and lower flanges. Suchfasteners are known in the art. The first module 52 includes a firstspiral reaction tube 76, the second module 54 includes a second spiralreaction tube 78, and the additional modules 56 each include anadditional spiral reaction tube 80. The spiral reaction tubes 76, 78,and 80 are operably connected in series via connector lines 74. Byvirtue of these connections a fluid flow is established from the inlet38 of the first spiral reaction tube 76 through the outlet 40 of thelast additional spiral reaction tube 80. Preferably the internaldiameter of the first and second spiral reaction tubes 76 and 78 areabout 0.75 inches. Preferably the spiral reaction tubes in subsequentmodules have an internal diameter that is larger, on the order ofbetween 1.5 to 3.0 inches. The larger diameter is necessary toaccommodate the increased viscosity of the reaction product as thepolyol chain grows and the increased volume of the reaction productwhile maintaining the turbulent flow characteristics.

[0017] Each module 52, 54 and 56 includes a heat exchanger connected toits heat exchange medium inlet 30 and heat exchange medium outlet 32.This design permits each module 52, 54, and 56 to have a differentreaction temperature. For example, it is advantageous when addingpropylene oxide as the [alkaline] alkylene oxide to have a higherreaction temperature, preferably 180° C. to 250° C., than when ethyleneoxide is the [alkaline] alkylene oxide being added. As would beunderstood by one of ordinary skill in the art, one or more modulescould share a common heat exchanger 58. Because of the continuous flowof the heat exchange medium, the temperature differential between theheat exchange medium and the reaction temperature is small. Said anotherway, the heat exchange medium is generally heated to the desiredreaction temperature in a given module 20.

[0018] Continuous reactor assembly 50 further includes a stock[alkaline] alkylene oxide tank 62 that is operably connected to theinlet 38 of the first spiral reaction tube 76 through a feed line 66. Apump 64 connected to feed line 66 pressurizes the [alkaline] alkyleneoxide in feed line 66 to a pressure of between about 200 to 1500 poundsper square inch. The actual pressure is chosen to be above the vaporpressure of the [alkaline] alkylene oxide to thus maintain the[alkaline] alkylene oxide in a liquid state through out the continuousreactor assembly 50. A stock initiator tank 68 is operably connected tothe inlet 38 of the first-spiral reactor tube 76 through a feed line 72.A pump 70 connected to feed line 72 pressurizes the initiator in feedline 72 to a pressure of between about 200 to 1500 pounds per squareinch. The [alkaline] alkylene oxide and initiator react to form aninitial reaction mixture in first spiral reaction tube 76 and to form areaction product as the initial reaction mixture exits the outlet of thefirst spiral reaction tube 76. A stock catalyst tank 82 is operablyconnected to the inlet 38 of the second spiral reactor tube 78 through afeed line 86 which connects to connector line 74. A pump 84 connected tofeed line 86 pressurizes the catalyst in feed line 86 to a pressure ofbetween about 200 to 1500 pounds per square inch. Both stock [alkaline]alkylene oxide tank 62 and stock catalyst tank 82 are operably connectedto the inlet of second spiral reaction tube 78 and additionally operablyconnected to additional inlets of additional spiral reaction tubes 80beyond second spiral reaction tube 78. Thus catalyst and [alkaline]alkylene oxide can be added to the reaction product of the first spiralreaction tube 76 at multiple points in the continuous reactor assembly50. Another [alkaline] alkylene oxide tank 88 is operably connected tothe inlet 38 of one or more of the additional spiral reactor tubes 80through a feed line 92 which connects to connector line 74 joiningadditional spiral reactor tubes 80. A pump 90 connected to feed line 92pressurizes the other [alkaline] alkylene oxide in feed line 92 to apressure of between about 200 to 1500 pounds per square inch to maintainthe other [alkaline] alkylene oxide in a liquid state. As will beunderstood by one of ordinary skill in the art, in some reactions it maybe advantageous if pumps 64, 70, 84, and 90 are operated at lowerpressures so long as the pressure is above the pressure in an associatedspiral reaction tube 36 so that the reactants flow into the continuousreactor 50.

[0019] The outlet of the last module is operably connected through afeed line 94 to a storage tank 96. The product leaving the final modulecan then be further processed to produce the final product, for example,a polyether polyol. In the continuous reactor assembly 50 shown in FIG.2 the catalyst is not added until after the [alkaline] alkylene oxidefirst reacts with the initiator. This can be beneficial when it isdesired to ensure that all of the reactive hydrogens on the initiatorare replaced with the [alkaline] alkylene oxide prior to adding catalystand beginning to build the polyol chain. As shown in FIG. 3, otherpolyol formation reactions are best performed by adding initiator,[alkaline] alkylene oxide and catalyst to the first spiral reaction tube76, thus in FIG. 3 the feed line 86 is additionally operably connectedto the inlet of the first spiral reaction tube 76. This is the onlydifference between the continuous reactor assembly 50 shown in FIGS. 2and 3.

[0020] In FIG. 4 an alternative embodiment of the reactor assembly ofFIG. 2 is shown at 150. The only difference in reactor assembly 150 isthat it is formed as a single module 20 having a plurality of spiralreaction tubes 36 operably connected to each other in series includingthe first spiral reaction tube 76, second spiral reaction tube 78 andadditional spiral reaction tubes 80. In addition, a single heat exchangemedium inlet 30 and outlet 32 recirculates a heat exchange mediumthrough a single heat exchanger 58 to provide a uniform temperature inthe continuous reactor assembly 150.

[0021] Now that the structure of the continuous reactor assembly 50 hasbeen described, its use to form several example polyether polyols willbe described. The continuous reactor assembly 50 shown in FIG. 2 wasused to form a polyether polyol wherein the first [alkaline] alkyleneoxide was ethylene oxide and the initiator was an aromatic initiatorhaving reactive hydrogens that are reactive to ethylene oxide. Oneexample of such an initiator is toluene diamine. When self catalyzinginitiators such as amines, like toluene diamine, or acids such asphosphoric acid are used it is preferred that all of the reactivehydrogens are reacted with the first alkylene oxide prior to adding anyadditional catalyst. Also, it is preferred that the free alkylene oxidelevel not exceed 25 weight % based on the total weight of the alkyleneoxide and initiator, thus it may be necessary to use multiple injectionsof alkylene oxide in multiple spiral reaction tubes 76 prior to addingcatalyst. When using ethylene oxide as the alkylene oxide and toluenediamine it is preferred that 4 moles of ethylene oxide be added to eachmole of toluene diamine prior to addition of catalyst. The ethyleneoxide is fed into the inlet 38 of first spiral reaction tube 76 under apressure of between 200 and 1500 pounds per square inch to maintain theethylene oxide in a liquid state. The initial reaction mixture ofethylene oxide and toluene diamine self catalyzes and becomes a reactionproduct during flow through the first spiral reaction tube 76 to form areaction product wherein ethylene oxide replaces the reactive hydrogenson the amines of toluene diamine. Preferably the stoichiometry of[alkaline] alkylene oxide to initiator is designed to produce a reactionproduct with very low concentrations of polymeric [alkaline] alkyleneoxide. In subsequent modules, after complete reaction of the ethyleneoxide with the reactive hydrogens on the toluene diamine, both ethyleneoxide and catalyst are added to form an elongated polyether polyolthrough the well know chain extension reaction. The preferred catalystsare potassium hydroxide, sodium hydroxide, alcoholates of potassiumhydroxide, alcoholates of sodium hydroxide, cesium hydroxide, amines,Lewis acid catalysts, or double metal complex catalysts, all of whichare known in the art.

[0022] At additional points in the continuous reactor 50 another[alkaline] alkylene oxide such as propylene oxide can be added to thereaction product. Because of the length of the spiral reaction tubes any[alkaline] alkylene oxide added to any module is substantiallycompletely reacted before the reaction product flows to the next spiralreaction tube. Thus, the process allows the formation of polyetherpolyols which are all of approximately the same length, thus reducingheterogeneity in the product. In addition, the design ensures that atany given time the amount of [alkaline] alkylene oxide in the reactionis low compared to a batch reactor and that the stoichiometry is bettercontrolled. This also enhances the quality of the polyether polyol. Themultiple addition points permit an operator to form a variety ofpolyols, for example, a polyether polyol having blocks of ethylene oxideand propylene oxide or a heteric polyol. As will be understood by one ofordinary skill in the art the separate heat exchangers 58 permit thereaction temperature to be changed during the reaction. This ability canbe useful to increase the yield of the reaction and the reactiontemperature will be determined in part by the identity of the [alkaline]alkylene oxide used in a given spiral reaction tube. The continuousreactor assembly shown in FIG. 3 will be used when it is not desirableto first replace all of the reactive hydrogens on the initiator with an[alkaline] alkylene oxide prior to beginning the elongation reaction.The reactor assembly 150 is more efficient when it is desired to run theentire reaction at a single reaction temperature.

[0023] Suitable [alkaline] alkylene oxides for use in the formation ofpolyether polyols include ethylene oxide, propylene oxide, and butyleneoxide.

[0024] Suitable catalysts include: the [alkaline] alkylene catalystssuch as potassium hydroxide, sodium hydroxide, alcoholates of potassiumhydroxide, alcoholates of sodium hydroxide, cesium hydroxide, or amines;Lewis acid catalysts such as boron trifluoride; and metal complexcatalysts such as double metal cyanide complexes. Preferably thecatalyst is added in an amount of 0.1% to 1.0% in a given addition.

[0025] Suitable initiators include amines and aromatic initiators havinghydrogens which are reactive with [alkaline] alkylene oxides. Preferredaromatic initiators include toluene diamine, hydroquinone, and otheraromatic initiators. Other initiators include the well knownnon-aromatic initiators which have hydrogens that are reactive to[alkaline] alkylene oxides such as glycerol.

EXAMPLE 1

[0026] A continuous reactor similar to that disclosed in FIG. 2 wasutilized in preparing the following example. Vicinal toluene diamine (amixture of 2,3-and 3,4-toluene diamine) was loaded into stock initiatortank 68 and kept under nitrogen pressure. Ethylene oxide monomer wasloaded into stock [alkaline] alkylene oxide tank 62 and also kept undernitrogen pressure (35 lbs. per square inch). Propylene oxide monomer wasloaded into the other [alkaline] alkylene oxide tank 88 and also keptunder nitrogen pressure. The vicinal toluene diarnine was injectedtogether with the ethylene oxide monomer into a first spiral reactiontube 76. The feed rate ratio of vicinal toluene diamine to ethyleneoxide monomer was 7.3:8.6 (w/w). The pressure upon injection into thefirst spiral reaction tube 76 was 995 lbs. per square inch and the heatexchange medium was at a temperature of 160° C. The reaction productexiting the first spiral reaction tube was passed into a second spiralreaction tube 78 wherein the heat exchange medium was at a temperatureof 210° C. Intermediate removed at this point in the reaction had ahydroxyl number of 758, and an amine number of 216, and a viscosity of6,200 centipoise at 120° F. The intermediate from the second spiralreaction tube 78 was injected together with an aqueous KOH solution(45%) and propylene oxide monomer mixture from the other [alkaline]alkylene oxide tank 88 into a third spiral reaction tube 80. The feedratio of intermediate to monomer mixture was 7.9:9.0 (w/w). The catalystconcentration of KOH was 0.2%. The heat exchange medium was at atemperature of 180° C. The reaction product from the third spiralreaction tube was passed through a fourth spiral reaction tube 80wherein the heat exchange medium was at a temperature of 230° C. Theproduct from the fourth spiral reaction tube was placed under highvacuum to remove unreacted [alkaline] alkylene oxide monomer. Theobtained product had a hydroxyl number of 395, and an amine number of103, and a viscosity of 6,600 centipoise at 80° F.

EXAMPLE 2

[0027] Example 2 was prepared similar to Example 1. Vicinal toluenediamine and ethylene oxide were fed into the first spiral reaction tubeat a ratio of initiator to monomer of 7.3:9.0 (w/w). The pressure at theinjection point was 660 lbs. per square inch and the heat exchangemedium was at a temperature of 140° C. The product from the first spiralreaction tube was passed through a second spiral reaction tube whereinthe heat exchange medium was at a temperature of 200° C. Theintermediate from the second spiral reaction tube had a hydroxyl numberof 749, and an amine number of 205, and a viscosity of 6,300 centipoiseat 120° F. The intermediate from the second spiral reaction tube wasinjected together with an aqueous KOH solution (45%) and propylene oxidemonomer mixture into a third spiral reaction tube. The feed ratio ofintermediate to propylene oxide monomer mixture was 7.2:8.9 (w/w). Thecatalyst concentration of KOH was 0.2% and the heat exchange medium wasat a temperature of 180° C. The product from the third spiral reactiontube was passed through a fourth spiral reaction tube wherein the heatexchange medium was at a temperature of 230° C. The product from thefourth spiral reaction tube was placed under high vacuum to removeunreacted [alkaline] alkylene oxide monomer. The product obtained had ahydroxyl number of 366, and an amine number of 94, and a viscosity of4,000 centipoise at 80° F.

EXAMPLE 3

[0028] Example 3 was prepared similar to Example 1. The vicinal toluenediamine and ethylene oxide monomer mixture were injected into a firstspiral reaction tube at a feed ration of 8.4:8.2 (w/w). The pressure atinjection was 650 lbs. per square inch and the heat exchange medium wasat a temperature of 140° C. The product from the first spiral reactiontube was passed through a second spiral reaction tube wherein the heatexchange medium was at a temperature of 200° C. The intermediate at thispoint had a hydroxyl number of 830 and an amine number of 297. Theproduct from the second spiral reaction tube was injected with aqueousKOH solution (45%) and propylene oxide monomer mixture into a thirdspiral reaction tube. The feed ratio of intermediate to propylene oxidemonomer mixture was 8.1:8.8 (w/w). The catalyst concentration of KOH was0.2% and the heat exchange medium was at a temperature of 180° C. Thereaction product from the third spiral reaction tube was passed into afourth spiral reaction tube wherein the heat exchange medium was at atemperature of 230° C. The product from the fourth spiral reaction tubewas placed under high vacuum to remove unreacted [alkaline] alkyleneoxide monomer and the product obtained had a hydroxyl number of 421 andan amine number of 143.

EXAMPLE 4

[0029] Example 4 was prepared similar to Example 1. To the first spiralreaction tube vicinal toluene diamine, ethylene oxide monomer, andaqueous KOH catalyst solution (45%) were injected into the first spiralreaction tube. The feed ratio of vicinal toluene diamine to ethyleneoxide monomer was 6.6:9.2 (w/w). The catalyst at this point had ahydroxyl number of 750 and an amine number of 139. The product from thesecond spiral reaction tube was injected together with propylene oxidemonomer mixture into a third spiral reaction tube. The feed ratio ofintermediate to propylene oxide mixture was 8.7:8.9 (w/w). The heatexchange medium was at 180° C. The product from the third spiralreaction tube was passed into a fourth spiral reaction tube wherein theheat exchange medium was at a temperature of 230° C. The product fromthe fourth spiral reaction tube was placed under high vacuum to removeunreacted alkylene monomer and the product obtained had a hydroxylnumber of 388 and an amine number of 69.

[0030] The present invention has been described in accordance with therelevant legal standards, thus the foregoing description is exemplaryrather than limiting in nature. Variations and modifications to thedisclosed embodiment may become apparent to those skilled in the art anddo come within the scope of this invention. Accordingly, the scope oflegal protection afforded this invention can only be determined bystudying the following claims.

In the claims:
 14. (amended) A continuous process of forming polyetherpolyols comprising the steps of: a) continuously forming an initialreaction mixture of at least one alkylene oxide and an initiator havingat least one reactive hydrogen which is reactive to said alkylene oxide;b) providing a plurality of spiral shaped reaction tubes operablyconnected to each other in series and each having an internal diameterbetween 0.25 and 3.0 inches, a spiral diameter of between 2 feet and 10feet, said spiral shaped reaction tubes promoting a pseudo-turbulentflow of said initial reaction mixture; c) continuously flowing saidinitial reaction mixture through said first of said spiral shapedreaction tubes to form a reaction product; d) flowing said reactionproduct into a second of said spiral shaped reaction tubes adjacent tosaid first of said spiral reaction tubes and adding a catalyst and analkylene oxide to said reaction product; e) surrounding said pluralityof spiral shaped reaction tubes with a heat exchange medium, said heatexchange medium establishing and maintaining a reaction temperaturewithin said plurality of spiral shaped reaction tubes of between 130° C.and 250° C.; and f) maintaining a pressure in said spiral shapedreaction tubes of between 200 to 1500 pounds per square inch. 18.(amended) A continuous process as recited in claim 14 wherein, step c)further comprises adding said catalyst to said initial reaction mixturein said first of said spiral shaped reaction tubes.
 19. (amended) Acontinuous process as recited in claim 14 further comprising the stepsof adding additional amounts of said catalyst and said alkylene oxide toothers of said spiral shaped reaction tubes.
 20. (amended) A continuousprocess as recited in claim 14 wherein step e) further comprises theadditional steps of establishing and maintaining a first reactiontemperature in a first plurality of spiral shaped reaction tubes andestablishing and maintaining a second reaction temperature in a secondplurality of spiral shaped reaction tubes, said second reactiontemperature being greater than said first reaction temperature. 21.(new) A continuous process as recited in claim 14 wherein the spiralreaction tubes curve in a continuous spiral, in the absence ofsubstantially linear tubes.
 22. (new) A continuous process as recited inclaim 14 wherein the spiral reaction tubes provide fluid flow from afirst spiral reaction tube inlet to a first spiral reaction tube outlet,in the absence of any fluid flow out of said outlet into said inlet. 23.(new) A continuous process as recited in claim 14 wherein the spiralreaction tubes comprise a continuously curved wall, said wall beingcontinuously curved in x, y and z planes.